Grinding machine



V- 2 1955 J. 1.. DAVIDSON, JR 2,724,217

GRINDING MACHINE Filed June 14, 1952 6 Sheets-Sheet 1 Q l I I P INVENTOR.

JAMES L. DAvmsou JR.

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ATTO R kl EYS Nov. 22, 1955 J. 1.. DAVIDSON, JR

GRINDING MACHINE 6 Sheets-Sheet 3 Filed June 14, 1952 II it! III II INVENTOR.

JAMES L. DAwDsoM JR.

ATTORNEYS 1955 J. DAVIDSON, JR 2,724,217

GRINDING MACHINE Filed June 14, 1952 6 Sheets-Sheet 4 IN VEN TOR.

JAMES L. DAvmsoN JR BY ATTORNEYS Nov. 22, 1955 J. L. DAVIDSON, JR

GRINDING MACHINE 6 Sheets-Sheet 5 Filed June 14, 1952 0. R J H E J MW w M w. 9 g HP y S. g M a i a. mA H MA H Z H Uq H HIIMTHH 3 5 ATTORNEYS 2 1955 J. DAVIDSON, JR 2,724,217

GRINDING MACHINE Filed June 14, 1952 6 Sheets-Sheet 6 INVENTOR. JAMES L. DAVIDSON Ja. BY

ATTORNEYS United rates Patent GRINDING MACHINE James L. Davidson, Jr., Marshall, Mich assignor to Eaton Manufacturing Company, Cleveland, Ghio, a corporation of Ohio Application June 14, 1952, Serial No. 293,506;

9 Claims. (Cl. 51-50) This invention relates to grinding and more particularly to a machine for grinding gears or rotors of specific peculiar form to prescribed size.

Broadly the invention comprehends a machine for finishing or grinding to desired precision and accuracy gears or rotors, such as the inner rotors of rotary pumps of the Gerotor type. Pumps of this type consist essentially of an outer ring or rotor having a plurality of identical teeth in its inner periphery equally, angularly spaced from one another, and equidistant from the central axis of the outer rotor, and an inner rotor having a plurality of teeth on its outer periphery one less in number than the outer rotor equally, angularly spaced from one another equidistant from the central axis of the inner rotor, and of a conjugate form to the teeth on the outer rotor. The inner rotor is adapted to be received within the outer rotor and mounted centrally thereto whereby upon rotation of the outer rotor and inner rotor, each about its own axis, the teeth of the inner rotor maintain substantial contact with the teeth of the outer rotor over a major if not the entire rotational position thereof so as to provide a plurality of pumping chambers between the cooperating inner and outer rotors, which chambers increase in volume in the direction of rotation from a position of full mesh between the teeth of the outer and inner rotors to the position of open mesh thereof and decrease in volume from the latter position to the former position in the direction of rotation of the rotors. It is essential in the construction of pumps of this type that a high degree of precision and accuracy be maintained between co-acting teeth of the inner and outer rotors; and accordingly, it is the premise of the instant machine to produce said result. The presently devised machine is an improvement over the machine covered by Patent No. 2,456,060, in that it is more economical in construction and affords a continuous even higher degree of accuracy than obtained by said patented machine. The continued high degree of accuracy of grinding operation of the present machine is primarily obtained through the ingenious use of constant angular velocity universal joints in association with gearing providing for an eccentric rotatable output from the machine.

Among the objects of the invention are the provision of a machine for grinding lobed rotors or gears, that;

1. Is capable of finishing said rotors to a high degree of precision and accuracy;

2. Assures uniformity of precision and accurate like ness among the several lobes of each rotor to be ground;

3. Is relatively simple in construction and easy to service;

4. Includes constant angular velocity universal joints in the make-up thereof to permit of a uniform and proper cycle of associated rotation and eccentric movement of the output member of the machine throughout a complete grinding operation;

5. Includes gearing in association with constant angular velocity universal joints, wherein through the selection of the gearing, the desired eccentric movement and speed of rotation relation of the output member of the machine can be obtained for a particularly numbered lobe rotor to be ground;

6. Includes floating spring force meshed gearing for insuring against backlash;

7. Includes spring means for creating tension to take the slack out of the universal joints used in the machine; and

8. Includes means for adjusting to close accuracy the eccentric ratio of operation of the machine.

Other objects and advantages of the invention will appear from the following description taken in connection with the drawings forming a part of the specification, and in which:

Fig. l is a side elevation view of a grinding machine, constituting the invention, in association with a grinding wheel, a wheel driven and drive means therefor;

Fig. 2 is a top elevation, partly cross-sectionalized view of the gearing system and associated input and output members drivingly connected therewith;

Fig. 3 is a cross-sectional view taken substantially along lines 3-3 of Fig. 2;

Fig. 4 is a cross-sectional view taken substantially along lines 44 of Fig. 3;

Fig. 5 is an enlarged cross-sectional view of the output head of the grinding machine;

Fig. 6 is an end elevation view of Fig. 5 looking in the direction of lines 66;

Fig. 7 is a side elevation view of a rotor holder;

Fig. 8 is an end elevation view of Fig. 7;

Fig. 9 is a side elevation partly cross-sectionalized view of the constant angular velocity joint assembly used in the machine;

Figs. 10 through 14 show five positions of a rotor being ground in relation to the grinding wheel for effecting a grinding operation;

Fig. 15 is an enlarged fragmentary end elevation view of the rotor-eccentric aligning adjusting means for the machine of Fig. 1; and

Fig. 16 is a cross-sectionalview along lines 16-16 of Fig. 15.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings for more specific details of the invention it) represents generally a grinding machine, driven by way of a coupling 12 from a motor 14 and wherein a grinding wheel 16 is arranged for grinding association therewith. The grinding machine 10 and a wheel dresser it are supported in spaced relation to one another on a standard 20.

The machine 10 includes a central housing 22, a head housing 24 and a rear housing 26 fixedly secured to the central housing respectively on opposite ends thereof with gear mechanism 23 of the machine disposed within the central housing, eccentric operating mechanism 30 in the head housing and an input shaft 32 journalled in the rear housing.

Gear mechanism 28 includes a gear 34 fixedly secured to input shaft 32 for rotation therewith, a gear 36, meshing with gear 34, fixedly secured at one end to a jackshaft 38, a gear fixedly secured to jackshaft 38 on the opposite end thereof from gear as, a gear 42 fixedly secured to a collar 43, which collar is in turn fixedly secured to one end of an eccentric sleeve 44 and an idler gear 46 in meshing relation between gears 40 and 42.

Jackshaft 38 is journalled for rotation in a support 48, which support is secured to a shaft journalled in housing 22, to permit of a pivoting of the jackshaft 38 toward and away from gears 34 and 42. The support 48 is fixedly adjustable as to meshing engagement of gears 34 and 36 and gears 40 and 46 by Way of an adjusting screw mechanism 52, threadingly secured and adjustablein housing taken substantially 22, having one end urging the support 48 in a direction toward gears 34 and 42. Tension adjustable springs 54 urge the support 48 in a like direction toward gears 34 and 42 as does screw mechanism 52. In this manner the gears are spring force meshed at all times and thus positively insure against backlash.

The eccentric operating mechanism 30 in the head housing 24 includes in addition to the eccentric sleeve 44 journalled on bearings 56 mounted in the housing, an arbor 58 journalled on bearings 68 mounted in the sleeve 44. The arbor extends axially in one direction beyond the open end 62 of head housing 24 and axially in the opposite direction centrally through an opening 64 in gear 42 into the central housing 22.

End 66 of arbor 58 is provided with an appropriate opening 68 for receipt therein of a rotor holder 70 and end 72 of the arbor 58 is secured in and forms part of one of a pair of Rzeppa type constant angular velocity universal joints 74 and 74 arranged at opposite ends of a shaft 76 therefor.

Idler gear 46 is secured to a shaft 78, which shaft 78 is in turn journalled in a bearing 80 mounted in a support 82.

The input shaft 32 is coupled to the electric motor 14 7 output by way of coupling 12 and thus derives its operation therefrom.

Rotor holder 70 is adapted to have a plurality of form cut inner rotors 84 secured thereon whereby as the grinder wheel is rotated in fixed axis relation thereto and the grinding machine placed in operation, a predetermined form finishing or grinding operation is carried out.

In viewing Figs. 2 and particularly, it is to be noted that rotation as imparted to the gear 42 is transmitted therefrom to the eccentric sleeve 44 whereupon as the sleeve is rotated the arbor is caused to be moved in an eccentric path relative to an axis of the head and rear housings 24 and 26.

The gear ratio to be used is determined by the number of lobes on the rotor to be ground and the relative speed between the arbor and eccentric sleeve is such, as illustrated by Figs. through 14, whereby the eccentric sleeve is rotated the number of times corresponding to the number of lobes on the rotor, while the arbor is rotated I once.

As a means for insuring of the alignment of the eccentric throw with the high point of a tooth on the rotor to be ground, a condition shown by Fig. 10, an adjustment means 86 is provided.

Adjustment means 86 includes an eccentric pin 88 mounted on gear 34 including an enlarged cylindrical portion 90 which is eccentric to an attached cylindrical portion 92 received in mounting relation in gear 34. A square block 94 is arranged in bearing relation on enlarged portion 90 and is adapted to be received in a parallel walled slot 96 of a plate 98. Plate 98 is fixedly secured to outer housing 100 of universal joint 74 and is adapted to be adjustably fixedly secured relative to gear 34 by virtue of its being clamped, as adjusted, between an. oblong plate 102 and face 104 of gear 34, with bolts 106 securing the assembly together. In this adjusted assembly as shown by Figs. and 16, the shaft 76 by way of universal joint 74 is connected directly to gear 34 and shaft 32 for simultaneous rotation therewith.

Whereas an adjustment can be made for alignment between the eccentric throw and the high point of a tooth of the rotor, to be ground, within the accuracy of one tooth, the eccentricity of pin 88 by way of block 94 will account for the final close adjustment necessary to give an accurate alignment as is shown by Fig. 10. In making an adjustment for relative angular movement between gear 34 and plate 98, so as to account for a relative adjustment movement between arbor 58 and eccentric sleeve 44, bolts 106 are backed off a sufficient amount to release plate 98 from fixedly clamped position between plate 102 and gear 34. As released pin 88 can be rotated effective to shift block 94 in slot 96 and thus establish a new adjusted setting between plate 98, housing and gear 34 whereupon the bolts 106 are again tightened and plate 98 clamped in its new adjusted position relative to gear 34.

For the purpose of insuring against slack developing in the universal joints, a pair of springs 108 are arranged in angularly disposed tensioned relation as connected between gear 34 and an annular flange 110 of housing 112 for universal joint 74. In the initial assembly of the springs 108 they are connected between gear 34 and flange 110 lying parallel to one another on opposite sides of shaft 76 and displaced substantially from one another. The gear 34 and housing 112 are next angularly rotated substantially 45 relative to one another so that the springs are placed in tension as shown by Fig. 1 effective to create a tension on the universal joints and take all the slack out of them.

In a normal operation of the grinding machine 10 with the grinding wheel rotated about an established axis for a grinding operation, unfinished form cut rotors mounted on the rotor holder 70 and with the motor placed in operation, rotation is imparted to the input shaft 32 by way of coupling 12. The rotation of the input shaft is transmitted therefrom in two paths, one by way of universal joint 7 4 connected at one end thereof and the other by way of gear 34. The rotation of shaft 32 as imparted to universal joint 74 is in turn transmitted by said universal joint to shaft 76, a second universal joint 74 at the opposite extremity of shaft 7 6, and by way of connection with the joint 74 to arbor 58 for the rotation of said arbor at the same rate of speed as the input shaft 32.

The rotation of gear 34 is transmitted to gear 36 through meshing relation therebetween, thence by way of jackshaft 38 to which gear 36 is secured, gear 40 connected at the opposite end of jackshaft 38, and from gear 40 to gear 42 by way of idler gear 46 having meshing engagement between the gears 40 and 42. Rotation of gear 42 is transmitted to sleeve 44 by way of collar 43 connected therebetween.

Through the provision of appropriate ratio gearing to finish grind a six love rotor 84, as disclosed by Figs. 10 through 14, the sleeve is made to rotate at six times the speed of the arbor whereby a complete eccentric throw of the arbor is obtained for each complete lobe that is ground.

The six to one speed ratio between the arbor and eccentric sleeve is maintained for the proper grinding of the rotor by reason of the fact that the eccentric is rotated reversely to the direction of rotation of the arbor. This condition is achieved through the utilization of the idler gear in meshing relation between gears 40 and 42 serving to reverse the rotation of gear 42 as it relates to the rotation of input shaft 32, gear 34, the universal joint assembly and the arbor 58.

In utilizing the universal joints 74 and 74 which are of constant angular velocity, the rotation of the input shaft 32 as transmitted to the eccentrically movable arbor by the universal joint assembly is maintainedconstant throughout each revolution notwithstanding the angular displacement of the shaft 76 connected between the universal joints. As such a constant ratio as provided in the gear mechanism is maintained thus assuring accuracy in the grinding of rotor 84 throughout each and every lobe thereof.

With the grinding wheel having a proper radius on the grinding periphery thereof, it is only necessary that the grinding wheel because of its circular form, he moved along a plane passing through the axis of the head housing efiective to grind one or more rotors arranged in juxtaposed posiiton to one another on the rotor holder 70.

Figs. 10 through 14 clearly show that as the grinding wheel remains fixed with relation to its axis, the rotors 84 are rotated and raised and lowered to thus generate grinding the proper peripheral surface onthe rotors.

While this invention has been described in connection with certain specific embodiments, the principle involved is susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention, therefore, is limited only as indicated by the scope of the appended claims.

What I claim is:

1. A machine for grinding lobes on a pump rotor comprising a power driven rotatable input shaft, means for supporting the input shaft for rotation, a rotatable arbor, means for supporting the arbor for rotation, universal joint means connected between the input shaft and arbor, means for actuating the arbor eccentrically to a fixed axis, and gearing means coupling the input shaft to the eccentric actuating means including a gear fixedly secured to the input shaft, 2. jackshaft, a gear fixedly secured to the jackshaft having meshing engagement with the gear secured to the input shaft, a second gear fixedly secured to the jackshaft axially spaced from the first gear on the jackshaft, a gear fixedly secured to the eccentric actuating means, an idler gear interposed in meshing engagement between the second mentioned gear secured to the jackshaft and the gear secured to the eccentric actuating means, means for supporting the idler gear for rotation, means for supporting the jackshaft for rotation and pivotal movement, means for urging the jackshaft, supporting means, the jackshaft and gears secured to the jackshaft in one direction for no backlash meshing of the gears on the jackshaft respectively with the gear secured to the input shaft and the idler gear, a grinding wheel, and means for supporting and rotating the grinding wheel for rotation about an axis perpendicular to the axis of the arbor and adapted to have engageable grinding relation with the pump rotor to be supported on the arbor.

2. A machine for grinding lobes on a pump rotor comprising housing means, an input shaft rotatably supported on an end portion of the housing means, a sleeve rotatably supported on an opposite end portion of the housing means about an axis coaxial with the input shaft, with the bore in the sleeve having an axis eccentric to the axis of rotation of the sleeve and input shaft, an arbor journalled for rotation on the sleeve in the bore thereof and extending axially in one direction beyond the one end portion of the housing means and in the opposite axial direction into the central portion of the housing means, said input shaft having a portion thereof extending axially beyond the end portion of the housing means in which it is rotatably supported and its axially opposite portion extending into the central portion of the housing, a universal joint assembly disposed in the central portion of the housing in interposed connected relation between the respective ends of the arbor and input shaft extending into the central portion of the housing, and gearing coupling the input shaft to the sleeve including a gear fixedly secured to the input shaft within the housing, a jackshaft rotatably supported in the central portion of the housing, a gear fixedly secured to the jackshaft, having meshing engagement with the gear secured to the input shaft, a second gear fixedly secured to the jackshaft, a gear fixedly secured with relation to the sleeve for rotation therewith, an idler gear, supported for rotation in the central portion of the housing, having meshing engagement with the second gear secured to the jackshaft and the gear rotatable with the sleeve, said gearing providing for the rotation of the sleeve at a speed equal to the number of lobes to be ground times the speed of the arbor, a grinding wheel, and means for supporting and rotating the grinding wheel for rotation about an axis perpendicular to the axis of the arbor and adapted to have engageable grinding relation with the pump rotor to be supported on the arbor.

3. A machine according to claim 2 wherein spring means are provided extending in connected relation be tween portions of the universal joints for imposing tension on the universal joints.

4. A machine according to claim 2 wherein means are provided for adjusting the eccentric relation between the arbor and sleeve.

5. A machine for grinding lobes on a pump rotor comprising a power driven rotatable input shaft, means for supporting the input shaft for rotation, motive means for driving the input shaft, a rotatable arbor, means for supporting the arbor for rotation, universal joint means connected between the input shaft and arbor for transmitting rotation between the input shaft and the arbor, means for actuating the arbor eccentric to a fixed axis, means for supporting the eccentric actuating means in encircling relation to the arbor, rotation transmitting means connected between the input shaft and arbor eccentric actuating means for rotating the eccentric actuating means in a reverse direction to the rotation of the arbor at a speed several times the speed of the arbor corresponding to the number of lobes to be ground times the speed of the arbor a grinding wheel, and means for supporting and rotating the grinding wheel for rotation about an axis perpendicular to the axis of the arbor and adapted to have engageable grinding relation with the pump rotor to be supported on the arbor.

6. A machine according to claim 5 wherein the rotation transmitting means includes a speed increasing gear system.

7. A machine according to claim 5 wherein the rotation transmitting means is a gearing system including a gear fixedly secured to the input shaft, a rotatably supported jackshaft, a gear fixedly secured to the jackshaft having meshing engagement with the gear secured to the input shaft, another gear fixedly secured to the jackshaft axially oppositely spaced from the other gear on the jackshaft, a gear fixedly secured to the arbor eccentric actuating means and an idler gear interposed in meshing engagement between the second mentioned gear secured to the jackshaft and the gear secured to the eccentric actuating means.

8. A machine according to claim 6 wherein the gear system includes a jackshaft, gears mounted near opposite ends of the jackshaft, means for supporting the jackshaft for pivotal movement and adjustable means for urging the support means in one direction for no backlash meshing engagement of the gears on the jackshaft with other gears of the system.

9. A machine according to claim 7 wherein means are provided for position adjusting the fixed securement of the gear relative to the eccentric actuating means to which it is secured so as to provide for the desired related gear tooth-eccentric position therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 222,901 Heckendorn Dec. 23, 1879 1,817,405 Braren Aug. 4, 1931 1,838,196 Sheehan Dec. 29, 1931 2,456,060 Hoern et a1 Dec. 14, 1948 

